Christie, who ruled out a run for the Oval Office himself just a week ago, said the other presidential hopefuls didn't come close to the former Massachusetts governor, whom he touted for his experience in both the private and public sector.

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"I've had conversations with a number of the other candidates. I have great respect for them, but in the end I don't think this was a close call for me," he told Fox News' Sean Hannity on Tuesday.

"I just believe that Gov. Romney is the person who gives us the best chance to beat Barack Obama next November," he added.

Christie made the announcement just hours before the Republican presidential debate at Dartmouth College.

Some analysts have speculated Christie is now vying to run on Romney's ticket, although the Jersey gov said Romney did not promise him anything in return for the endorsement.

Christie also left it up in the air if he'd want to be vice president.

"I just can't imagine it," he said. "The bottom line is you don't run for something like that.

"The fact is whoever the nominee of our party is - and I believe it's going to be Gov. Romney - will have the opportunity to make the choice of the person he thinks will best serve him as a running mate…That's going to be his call as the nominee of the party…I'm not going to worry about stuff that I have no control over."